Telomeres and Cancer #11

Question 1

why might the extreme 3’ end of the lagging strand not be copied

Answer 1

because the final okazaki fragment canno be primed as the natural position for the priming site is beyond the end of the template

Question 2

shortening of chromosomes happens majorly in which strand?

Answer 2

lagging strand

Question 3

what are telomeres?

Answer 3

they are tandem repeats of a hexamer (GGGTTA) that is present 100’s of times at the tips of each chromosome

Question 4

how can telomeres be extended independently to the replicative process?

Answer 4

by telomerase, which has an RNA template of AACCCC

Question 5

telomerase

Answer 5

is a protein RNA complex that carries an RNA template for synthesizing a telomere sequence. IT IS A RIBONUCLEOTIDE PROTEIN

Question 6

explain how a telomerase works

Answer 6

~the telomerase RNA (TERC/TR) is used as a template for each extension step
~the protein part (TERT) is a reverse transcriptase which carries out DNA synthesis

Question 7

the Hayflick limit

Answer 7

know that the telomeres shorten by 50-100 nt after every division, eventually becoming too short for efficient replication. This puts the cells into replicative senescence. This is the hayflick limit. NOTE that if you introduce telomerase into the solution they may proliferate forever

Question 8

what is a target in cancer therapy

Answer 8

telomerase